With the development of the ultra-thin liquid crystal display device, a backlight module normally adopts glass as the material of a light guide plate to maintain the mechanical strength of a liquid crystal display module at present. Glass is relatively suitable to function as the material of the light guide plate because of its characteristics such as high transparency, high mechanical strength, and convenient ink pattern transferring capability or the like. However, in the case of glass being used as the material of a light guide plate, the absorbance of the glass with respect to blue light, which is located at the short wavelength range, is higher than organic glass, which is the another kind of material for the light guide plate, because of the material properties of glass; the longer the propagation distance in a glass light guide plate of the white light emitted from a backlight source is, the more blue light is absorbed, thereby the problem that the color of the back light turns to yellow can be caused. The problem can become even severer for a large-sized display device, whereby the color of the back light provided by the backlight source can become inhomogeneous due to different positions, and therefore the quality of the displayed image can be adversely impacted.
Therefore, it is a critical problem for those skilled in art to ameliorate the problem that the color of the back light turns to yellow because blue light is absorbed by a light guide plate, and the display effect is adversely impacted.